SAT Subject Test Mathematics Level 2

The answer is (D).

HIDDEN SPECIAL TRIANGLES

It happens a lot that the key to solving a geometry problem is to add a line segment or two to the
figure. Often what results is one or more special triangles. The ability to spot, even to create, special
triangles comes in handy in a question like Example 4.

ADD TO THE FIGURE

Often   the breakthrough    on  a   plane   geometry    problem comes   when    you add a   line    segment

or  two to  the figure. Perpendiculars  can be  especially  useful. They    can function    as  rectangle

sides   or  triangle    altitudes   or  right   triangle    legs.

Example 4

Figure  4

In  Figure  4,  the perimeter   of  isosceles   trapezoid   WXYZ    is  62. If      =   7   and     =   25, what    is

the length  of  diagonal    WY?

1.

(A) 15

(B) 17

(C) 20

(D) 25